How can i play a sound file same time?

Hy guys!

I would like to transfer the caller to an agent such that the caller and the callee hear a sound file same time. It is necessary to make easier the agents work (They don’t wana say always like this “Good day, can i help you?.”). The plan is that the agents record theirs “welcome voices” and play every time when they start the communication with the user/caller. The welcome sound playback must be played same time between the agent and the caller.

I am looking for the solution for many days but I could not found anything.

I tried solve this problem with Dial:


and MeetMe or ConfBridge:

sound_join = yes

Every solution play the sound file sequentially and not same time.

I hope somebody culd help me and understand my problem.
I use Asterisk 1.8 and 11.

Thank your time!